This invention relates to tripot style joints, and more particularly, this invention relates to a tripot joint having a retainer for needle rollers.
A tripot style joint is usable as one type of constant velocity (“CV”) joint on a drive axle of a vehicle. A CV joint is used to transfer a uniform torque and a constant speed, while operating through a wide range of angles. The CV joint is preferably quite compact so as to allow the drive axle to rotate at a constant velocity, regardless of the operating angle.
Turning now to FIG. 1, a tripot style joint 10 includes a tripot housing 12 formed with a ball guide, the interior grooves of the housing 12. That is, the housing 12 has an offset radius profile for the ball bore and an outer ball guide to help track the outer ball relative to the housing axis. A tripot spider 14 includes a somewhat spherical trunnion 16, a ball assembly 18 having an inner ball 20, a complement of needle rollers 22, and an outer ball 24. The inner ball 20 has a spherical radius profile on the inner diameter that mates to the spherical profile of the spider trunnion 16 and a cylindrical outer diameter that mates with the needle rollers 22. The compliment of needle rollers 22 mates to the outer diameter of the inner ball 20 and the inner diameter of the outer ball 24. The outer ball 24 has a cylindrical inner diameter and a radius profile outer diameter to match the ball bore of the housing 12. As shown in FIG. 2, the inner diameter of the outer ball 24 is designed with two shoulders 26 that form a cup. The cup area contains the compliment of needle rollers 22.
The primary function of such a tripot joint 10 is to reduce axial forces generated during the operation of the joint 10 within a vehicle. The generated axial forces create a ride disturbance in the vehicle called “shudder”. The reduction to the generated axial forces is accomplished by tracking either the outer ball 24 or the ball assembly 18 relative to the axis of the housing 12.
A problem with the joint design shown in FIG. 1 is the design of the outer ball 24. The inner diameter profile of the outer ball 24 that forms the cup shape is very expensive to manufacture.
U.S. Pat. No. 5,658,199 to Ricks et al. describes an alternative to the cup design which uses two securing rings. Because of the design of the securing rings, the width of the outer ball must be increased to accommodate grooves for the retaining rings. Any increase to the width of the outer ball requires the overall diameter of the housing to be increased. Therefore, affecting both the package size and the mass of this style joint.